Was Jimi Hendrix spinning out of control during his final days in the studio, or on the verge of a new breakthrough? New evidence emerges on People, Hell and Angels, a new album of previously unreleased studio recordings.

Bassist Billy Cox has fond memories of his final days in the studio with Jimi Hendrix, recording at New York’s famed Record Plant in 1969.

But trips to and from the studio with Hendrix were another matter entirely. Cox recalls that the legendary guitarist was something of a reckless driver. A jaunt across Manhattan in Jimi’s silver Corvette could be a hair-raising experience.

“We’d go into the studio around eight o’clock in the evening,” Cox remembers, “and a lot of times we didn’t come out until noon the next day. When we came out of the studio, he’d have his guitar, I’d have my bass…and the Corvette was a two-seater. So we take off, and my face is hangin’ out the window, along with one of my legs, and Jimi’s got his guitar in the back. We’re goin’ through traffic, and I’m sayin, ‘Oh, lord, you gon’ run into somebody!’ He scared me. I’d get out at the hotel and say, ‘Whew, man! I made it safe and sound.’ ”

As fate would have it, it was drug-and-alcohol-related asphyxiation, not reckless driving, that claimed Hendrix’s life not long after the scene Cox relates. But by then, Jimi had already vastly enriched rock guitar’s lexicon of licks, tricks and aesthetics. He raised the bar for rock guitar heroism. Or as Cox puts it, “Here we are 42 years later, and we’re still celebrating his genius.”

Hendrix never got to finish the album he was working on at the time, leaving fans, rock historians and pop culture geeks perpetually wondering what he was up to in the studio during the final year and a half of his life. Back at the tail end of the Sixties, some said he’d lost the plot, that the glory days of Are You Experienced, Axis: Bold as Love and Electric Ladyland were behind him, and never to return.

Then again, there were those who said that he was on the verge of creating some new progressive form of music exponentially more revolutionary than what had come before. There was talk of a collaboration with Miles Davis arranger Gil Evans, although there’s not even a hint of that among the mountain of unfinished tapes Hendrix left behind.

“Jimi was frustrated before he died, because I think the public didn’t understand him,” says Eddie Kramer, the recording engineer who worked most extensively with Hendrix throughout his years of fame. “He was so confused as to which way to go.”

So was Hendrix on a crash course with musical disaster, wasted on dope and wasting tape while the studio clock ticked off dollars? Or was there some grand, redeeming vision that would have turned the whole thing into another Sgt. Pepper’s, Bitches Brew or Exile on Main Street?

Elucidating the musical truth of Hendrix’s final recordings has been the almost 20-year mission of Kramer, archivist/producer/historian John McDermott, and Janie Hendrix, who is Jimi’s half sister and the head of Experience Hendrix, the company that manages the late guitarist’s estate.

In 1997, they released their best educated guess as to what that final album might have been. It was called First Rays of the New Rising Sun, the name that they conjecture was at the top of Hendrix’s list of tentative titles for his work-in-progress.

They followed it up in 2010 with Valleys of Neptune, another scoop from Hendrix’s deep barrel of end-game demos, work tapes, jam tapes, party tapes, unfinished masters and so on. McDermott, Kramer and Experience Hendrix recently dropped another glimpse of Hendrix’s final days at work in the studio, People, Hell & Angels.

“We’re filling in the library with the last missing piece, from a thematic point of view,” McDermott says. “On Valleys of Neptune, we looked at the final recordings of the Jimi Hendrix Experience and then Jimi’s first steps with [bassist] Billy Cox. ‘Here,’ we said. ‘This is Jimi outside the Experience.’ So it includes the very first recordings the Band of Gypsys made in the studio, Jimi with the band he had at Woodstock and him playing and guesting with friends like [R&B sax man] Lonnie Youngblood and [vocal duo] the Allen twins. The idea for us was to say, ‘This is all the stuff that was among his portfolio of music that was cut after Electric Ladyland.’ Hopefully it shows some of the avenues that this guy was traveling down as he was trying to decide what the future held.”

The tracks span the period from March 13, 1968, through August 1970, although the main focus is on an extended run of sessions held at the New York Record Plant in mid 1969. It was a time of profound change for rock music and for Hendrix himself. He’d just moved back from London, where he’d first risen to fame and where he recorded the Jimi Hendrix Experience’s game-changing first three albums. He was back in his home country, but all was not well.

Hendrix had parted company with Chas Chandler, his co-manager and the producer who had given shape and substance to the first three Experience albums. Experience bass player Noel Redding would soon leave the fold as well. Redding and Chandler were both exasperated by the guitarist’s newfound fondness for tinkering endlessly with musical ideas in the studio and only occasionally coming away with a master take.